re: "I want to complete his work and only fix his mistakes"
I would like that to happen as well. But there are two major problems:
a) I am not sure that he knows how to complete this work or fix all of the problems with your system.
b) The freelancer doesn't work for you. You have no contract with the freelancer, and it would be a violation of Upwork ToS for you to ask him to do any work. Moreover, the freelancer does not work for Upwork. Upwork can not "order" the freelancer to continue working on your behalf.
I'm sorry about your experience with this freelancer. Our team will reach out to you directly to assist you with this report and advise on further steps.
I hope Upwork is able to help you.
Don't rule out the possibility of incompetence or insufficient skill.
ALL of the following may be possible:
a) the feelancer is incompetent
b) the freelancer is a cheater
c) the freelancer is both a cheater AND incompetent
d) something else
You really should have checked the work before paying and closing the account. Clients are given 14 days to pay freelancers after work had been submitted.
I doubt that Upwork will help you. I also very much doubt you will be able to change the feedback you left. Your best bet is probably to leave it, stop wasting Upwork resources, and put this down to experience. If/when you hire again, select your freelancer carefully and check the work thoroughly before paying anything.